Fume hoods are well recognized in the art as providing a protective environment in which hazardous materials may be safely handled, particularly where the hazardous material is in a liquid or gaseous form. These hoods are designed to capture and pull or direct fumes safely away from a person or equipment which is with or associated with the hazardous material. A fume hood of the prior art is shown in U.S. Pat. No. 2,702,505, issued to Laurence N. Nelson, on Feb. 22, 1955. Inside the fume hood is a countertop which provides a working surface on which there may be placed various items such as containers of various materials and equipment. A typical countertop is seen in Nelson FIG. 1 at 2. It is such a countertop to which the present invention is directed.
Fume hood countertops typically have a uniform, level surface that is recessed in the central top portion thereof to define a type of reservoir to contain spills of liquids and the like. These reservoirs in the prior art countertops are necessarily shallow and poorly designed for ensuring the desired capture of spills. The shallowness of these prior art reserviors is due to the relative thinness of the countertop which is desirable to reduce the weight and cost of the countertop. Currently countertops for fume hoods are manufactured from slabs of epoxy resin. This material is relatively inert to most chemicals, but is relatively easily scarred, scratched or discolored and is not easily worked by common cutting tools. The nature of the epoxy resin is such that repair of spot damage to the countertop is not often practiced in that the epoxy resin cannot be sanded or buffed to a sufficiently smooth surface using the usual field maintenance tools and methods. Thus, the prior art epoxy resin countertops most often must be replaced when they suffer only spot damage, hence the need to minimize the cost of the countertop by making it as thin as practicable, hence the use of shallow reserviors which are less than suitable for containing spills and providing the desired protection of a person using the hood and the environment ambient to the exterior of the hood.
A typical feature of a fume hood countertop is a cupsink. A cupsink generally comprises an opening through the thickness of a countertop which receives therein a type of flanged cup. The cup may have a closed bottom in which case it serves to contain liquids or solids placed therein. Or, the cup may have a discharge opening in its bottom, this discharge opening being connected to a pipe, hose or the like that leads to a larger receptacle or to the sewer. Typically the cupsink is small and positioned in one or more of the corners of the countertop.
As noted above, typically prior art fume hood countertops are made of an epoxy resin. While this is useful in that the countertops are long-lived, durable, and non-reactive to most chemicals that spill on the surface of the countertop, the epoxy resins are not easily machineable, sandable, or field workable. Such epoxy resins are also easily scratched. They are discolored by certain chemicls, and the discoloration remains even after cleaning.
Finally, the prior art epoxy resins used in the manufacture of fume hood countertops are dark-colored. Often, it is advantageous to the user to have a white or light-colored background against which to conduct their activities within the hood.
The typical prior art fume hood countertop also employs sharp (e.g. 90.degree.) angles at the juncture of the sidewalls of the reservoir thereof and the bottom of the reservoir, and the top surface of the countertop. Effective cleaning in the crevices created by such angles is at the best difficult and time-consuming, and at the worst is not possible.
Certain regulatory agencies require fume hood countertops to have a safety zone demarcation line clearly defined on the countertop near the front opening to the fume hood and extending between the opposite sides of the fume hood. The placement of this safety line is such as to define the permissible working area of the countertop interiorly of the fume hood and within which the air flow from outside the hood and into and out the exhaust of the hood, is effective to prevent fumes from escaping out the front opening of the hood. No material is to be placed forwardly of this safety line. Typically, these lines are merely painted on or comprise a colored tape which is adhered to the countertop. Thus, after short terms of use, the line is abraded away by reason of the movement of materials and equipment thereacross during loading of the hood, and by reason of abrasive cleanings. Painted lines and tapes are less resistant to corrosive environments than is the epoxy resin countertop so that over time the prior art type of lines tend to fade or become indistinguishable from the countertop itself.
Therefore, it is an object of this invention to provide an improved countertop for a fume hood or like enclosure that reduces the likelihood that a liquid spill within the hood will escape the hood.
Another object of the present invention is to provide a countertop for a fume hood or like enclosure wherein the countertop includes a novel and improved safety zone demarcation identifier.
Other objects and advantages of the present invention will be recognized from the description provided herein including the claims and the drawings in which:
FIG. 1 is a representation of a prior art fume hood and embodying various of the features of the present invention;
FIG. 2 is a top view of a countertop for a fume hood and embodying various of the features of the present invention;
FIG. 3 is a sectional view taken generally along the line 3--3 of FIG. 1;
FIG. 4 is a sectional view taken generally along the line 4--4 of FIG. 1;
FIG. 5 is an enlarged view of a portion of the left hand end of the countertop as depicted in FIG. 3;
FIG. 6 is an enlarged view of a portion of the right hand end of the countertop as depicted in FIG. 3;
FIG. 7 is an enlarged view of the opposite ends portions of the sectional view of the countertop depicted in FIG. 4; and
FIG. 8 is an enlarged view as in FIG. 5, and depicting an alternative embodiement that includes a secondary liquid spill capture trough.